1. Field of the Invention
The field of this invention relates to fat-containing protein food products, particularly meat analog food products formed from fibrous texturized protein.
2. Description of the Prior Art
A variety of fat-containing protein food products are known in the prior art. A problem associated with many such food products is that the fat phase separates from the protein phase. It is often desirable, however, to maintain the fat phase intimately admixed with the protein phase.
A particular example of a protein food product wherein it is desirable to maintain the fat phase admixed with the protein phase is a meat analog food product formed from texturized vegetable protein.
A variety of prior art processes are known for "texturizing" vegetable protein, i.e., imparting to vegetable protein a fibrous, filamentary structure and toughness associated with meat, and assembling the texturized protein into familiar meat forms to provide meat analog products. For example, meat analog products can be made by processes involving fiber spinning or thermal plastic extrusion.
The fiber spinning technique is an adaptation of the spinnerette method of making synthetic textile fibers. In the meat analog adaptation of this method, fibrous protein products are prepared from proteins such as a soy protein by forming a spinning dope from alkali solubilized protein and extruding the dope through a perforated die (spinnerette) into an acid (isoelectric) precipitating bath. The acidic bath sets the filaments or fibers as they emerge from the spinnerette. Thereafter, the fibers are collected for subsequent processing. The fibers, during the collection process, are usually stretched to orient the molecular structure of the fibers; thereafter, the fibers are assembled in "tows", bundles of individual fibers aligned in parallel fashion. Binding agents, coloring, fat and flavor may be added to the fiber tows and the entire fiber mass is then shaped to resemble familiar meat products. Details regarding the techniques are disclosed, for example, in U.S. Pat. Nos. 2,682,466; 2,730,447 and 2,730,448.
The thermal plastic extrusion method of forming meat analog products is an adaptation of technology involved in making ready-to-eat cereal food products. The thermal plastic extrusion process involves preparing a mixture of protein material, water, flavor and other ingredients and thereafter feeding the mixture into a cooker extruder wherein it is subjected to heat and pressure and subsequently extruding the mixture. The extrudate filament as it enters into a medium of reduced pressure (usually atmospheric) expands to form a fibrous cellular structure. On rehydration, the fibrous filamentary product can possess an appearance, a bite and mouth feel comparable to cooked hamburger. Details regarding thermal plastic extrusion techniques for the forming of meat analogs are disclosed, for example, in U.S. Pat. Nos. 3,102,031 and 3,488,770. Wtih the use of suitable binders, products similar to hamburger patties, meat balls, meat loaves and meat chunks can be formed. A variety of other processes are known for providing very suitable meat analog products which approach the texture and appearance of a variety of natural meats.
Providing meat analog products having the basic appearance and fibrous texture of meats solves only a portion of the problem of providing desirable meat analogs which are substantially indistinguishable from real meat. Incorporating desirable fats and flavors in the meat analog is necessary to provide fully satisfactory meat analogs.
Incorporating nutritionally desirable liquid fats (oils) can be difficult because the liquid oil tends to separate from the protein filaments of the meat analog. The use of higher melting fats can be helpful, but on heating the product, these fats too tend to separate from the product. In addition, very high melting fats are less desirable nutritionally and can have an undesirable waxy mouthfeel.
Ethyl cellulose is a known item of commerce which has a wide variety of industrial applications, for example, in fields relating to coatings and pharmaceuticals. (See, Ethocel for Coatings Applications, The Dow Chemical Co., Copyright, 1966). Heretofore, it was known that this material can thicken vegetable oils (see, U.S. Pat. No. 2,796,381).
It would be desirable in fat-containing fibrous protein food products to stabilize the fat to provide the fat in a viscous or gelled state in order to inhibit separation of fat from the protein. To be acceptable, however, it is critical that the stabilized fat present an acceptable mouthfeel, i.e., to be acceptable, the stabilized fat cannot be slimy, sticky, gummy or waxy. In addition, it would be desirable to improve the flavor of fibrous protein food products.